Repalce 4164 RAM by 41464
Dear all,
I have some amount of 41464 DRAM from old PC VGA card which are useless at the moment. I think to keep them as a spare for the upper 32k Ram made of 4164.
My question: Did someone already replace 4264 by 41464? Much much effort is it?
Thanks and Rgs,
Stephan
I have some amount of 41464 DRAM from old PC VGA card which are useless at the moment. I think to keep them as a spare for the upper 32k Ram made of 4164.
My question: Did someone already replace 4264 by 41464? Much much effort is it?
Thanks and Rgs,
Stephan
Post edited by maskenlos on
Comments
The pin-outs are different, but not that much different if you use a socket to make an adaptor (or just bend the relevant pins up before fitting to the the PCB).
Apart from physically fitting, the bigest problem is that the 41464 DRAM is designed for a 8 bit 256 cycle refresh (the Z80 CPU only does a 7 bit 128 cycle refresh using A0 to A6). So if you are only going to use 32k of the available 64k addresses, make sure that the inputs to the address multiplexers, and then to the 41464 DRAM are correct.
The 41464 can also do it's own auto-refresh, but you have to change the /CAS and /RAS timings to get this to work.
I have come across a comment where someone reported that they had got two 41464 DRAM chips working, but it was a while ago, and I don't remember where...
If you are successful, do report back ;).
Mark
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